[Bug c++/99550] New: ICE (segfault) on arm with -std=c++2a

[Bug c++/99550] New: ICE (segfault) on arm with -std=c++2a

[delleyves at gmx dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99550

            Bug ID: 99550
           Summary: ICE (segfault) on arm with -std=c++2a
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: delleyves at gmx dot ch
  Target Milestone: ---

The following code segfaults on "arm-gcc 10.2.1 (none)" (as found on
godbolt.org) when compiled with `-std=c++2a`, but not without that flag.

So does the official ARM GCC release gcc-arm-none-eabi-10-2020-q4-major on
Ubuntu.

On my OSX however, it doesn't segfault. Neither does the x86-64 gcc 10.2 on
godbolt.

```
#include <type_traits>

template <typename value_type_>
struct JoinedRange {
  using value_type = value_type_;
  template <bool is_const>
  struct Iterator {
    template <typename T>
    using maybe_const_t = std::conditional_t<is_const, const T, T>;

    template <bool>
    friend class Iterator;

   public:
    using value_type = JoinedRange::value_type;
    using reference = maybe_const_t<value_type>;
    using pointer = maybe_const_t<value_type>*;
  };
  using iterator = Iterator<false>;
  using const_iterator = Iterator<true>;
};

template class JoinedRange<int>;
```

[Bug c++/99550] ICE (segfault) on arm with -std=c++2a

[delleyves at gmx dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99550

--- Comment #1 from Yves Delley <delleyves at gmx dot ch> ---
See https://godbolt.org/z/ErEh55 
Bug also submitted at https://bugs.launchpad.net/gcc-arm-embedded/+bug/1918693
Which is the right tracker for this?

[Bug target/99550] ICE (segfault) on arm with -std=c++2a

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99550

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced:
template <typename value_type_>
struct JoinedRange {
  struct Iterator 
  {
    template <typename T> using maybe_const_t = T;
    using pointer = maybe_const_t<int>;
  };
};
JoinedRange<int> a;

[Bug target/99550] ICE (segfault) on arm with -std=c++2a

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99550

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 96805.

*** This bug has been marked as a duplicate of bug 96805 ***